278 Scientific Intelligence. 
between the tissues and oxygen, this last becomes absorbed, (producing 
the destruction of the tissues) ; ‘this happening in the first part of the 
capillary system, and the blood behind being charged with the same gas, 
and the same attraction existing, the first portion after losing its oxygen 
and consequently its attraction for the sides of the vessel, is pushed on- 
ward by the arterial blood from behind responding to the attraction of the 
tissues, when it in turn loses its oxygen, and is pushed forward by an- 
other bree thereby causing a continuous flow from the arterial to 
the venous system. 
With the pulmonary circulation the reverse takes place—the venous 
blood passes onwards, pushing forward the arterial.. Here the air cells 
of the lungs, along which the capillary system of the pulmonary ves- 
sel passes, contain oxygen, between which and the venous blood there 
is considerable attraction, but none between it and the arterial ; so when 
the venous blood becomes charged with oxygen, it loses its attraction 
for the walls of the nose gh and is pushed onward —_ venous blood 
not yet acted upon. 
The portal circulation is style; ina Singites way. ‘ilatwonsh the 
portal blood and the structure of the liver there is an energetic affinity, 
betrayed by the circumstance that a chemical decomposition takes 
place, and bile is separated ; and that change completed, the residue, 
which is no longer acted upon, forms the venous: blood of the hepatic 
veins, and is driven onwards by the affinities taking place between the 
blood and the substance of the liver. Another power which aids — 
in Soicing te blood from the portal into the hepatic veins, is the pas- 
sage of the blood from the hepatic arteries into the portal veins, which 
is brought about by the cause alluded to! in speaking : the emer: 
circulation. 
The author also alludes to the fetal sindidetion in the “pina 
which is similar to the pulmonary circulation,—deoxydized passing on- 
ward toward oxydized blood. The umbilical arteries carry in their sp* 
ral courses, as they twist round the umbilical vein, the effete blood of 
the foetus, and distribute it by their ramifications to the placenta. la 
that organ it is brought into relation with the arterial blood of the mot 
er, which oxydizes it, becoming by that act deoxydized itself. The fe- 
tal blood now returns along the ramifications of the umbilical vein, and 
finally is discharged from the placenta by a single trunk 
|The application of the principle here set forth, Soapiiliens very fel 
citous explanation of a great number of effects which we witness. It 
is well known that after ordinary death, whilst the arteries are empty, 
the systemic veins and also the right cavities of the heart are full of 
ete ae _ The reason is clear, Tas penta theory, that 
the hea ell known to explain 
